Unfortunately, because no news station or paper wants to cover this, the only place I could find it is a Political Action Group website, but I did find the full text of the bill now turned law.
The bill has been on the books, but has finally signed into law 16 years after the State Supreme Court ruled that the current sodomy laws were declared unconstitutional in Gryczan v Montana (1997). The bill was signed into law, and will take effect next Fiscal Year, October 1, 2013.
What does this mean? Montana has now legalized oral sex, anal sex, beastiality, penetration of the mouth, anus, or vagina with a marital aid, phallic shaped fruit or vegetable, rim jobs, et cetera.
How long til Montana allows homosexual marriages? No idea. If it took them 16 years to officially repeal the Sodomy/Deviant Sexual Acts Laws that were declared unconstitutional by the Montana State Supreme Court in 1997 and the United States Supreme Court in 2003, don't expect them to approve it over night, I'd guess it will take at least another 20 years.